Fix prometheus test race condition

[otherview]

Description

Fixes # https://github.com/vechain/protocol-board-repo/issues/211

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] New and existing E2E tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 61.88%. Comparing base (b9047c0) to head (6e5be0f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #759 +/- ## ======================================= Coverage 61.88% 61.88% ======================================= Files 202 202 Lines 18696 18696 ======================================= Hits 11570 11570 Misses 6015 6015 Partials 1111 1111 ```

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